San Martín de Unx is a town and municipality in the province and autonomous community of Navarre, in northern Spain. It is one of the many small municipalities that make up this region of northern Iberia.
Navarre is an autonomous community and province situated in northern Spain, bordering France to the north. San Martín de Unx lies within this territory, sharing in the administrative structure common to Navarrese municipalities, which are governed locally as towns and municipalities.
As a municipality, San Martín de Unx serves as the local administrative unit for the town and its surrounding area. It is located in the northern part of Spain, within the broader Navarre region.